The present invention is directed to a float actuated shutoff valve to terminate the flow of fuel into a storage tank to prevent overfilling of the tank.
The valve of the present invention is particularly adapted for controlling the filling of aboveground fuel storage tanks. These tanks are filled by pumping fuel from tank trucks by means of a large diameter hose which sealingly couples to the upper end of fill pipes during the filling operation. Because of the relatively large capacity of the storage tanks, a relatively high flow rate during the filling operation is desirable and flow rates in the general range of 200 gpm are typical. As a result of these high flow rates, it is quite common that the tank is overfilled resulting in a spill. As much as 25 gallons of fuel may be involved in such a spillage. To prevent the spillage from contaminating the soil, it is now required in many locations that the fill pipe be equipped with an overfill storage container. However, prevention of overfilling of the tank is obviously the more desirable solution.
To prevent overfilling, many present day aboveground storage tanks are provided with a float actuated valve which closes when the level of fuel within the aboveground storage tank rises to a predetermined level, for example, when the tank is 90% full.
Although the recommended practice for an aboveground storage tank is to fill no more than 90% of the tank to allow for thermal expansion, the distance from the top of the storage tank to the fuel when the storage tank is at 90% capacity can vary greatly from tank to tank. On large diameter tanks, the free space of a 90% full tank can be a distance of 8 inches or more. On small diameter, square, or rectangular tanks, the free space or distance of the fuel from the top of the storage tank may be as small as an inch when the tank is filled to 90% capacity.
With previously known actuating shutoff valves, the position ofthe floats relative to the valve body requires at least 9 inches between the top of the tank and the center line of the float at shutoff. As a result, any storage tank with less than 9 inches of free space could not be filled to 90% capacity.
The present invention is directed to a solution to the aforementioned concerned. According to the present invcntiori, a valve assembly is provided extending downward through the top of the aboveground fuel storage tank. The valve assembly includes a cylindrical valve housing mounted to the lower end of the fuel pipe which extends downward through a riser welded to the top of the storage tank. The valve housing provides a fluid flow passageway in which incoming fuel is directed downward into the storage tank uader pressure. A hollow cylindrical float assembly is provided at the top portion of the valve assembly and is coaxially mounted along the outside surface of a pipe leading into the storage tank. The float slides vertically along the pipe with the fluctuation of the fuel level il the storage tank. A series of linkage assemblies connect the float to a poppet. A valve seat is provided in the fluid flow passageway such that when the poppet is closed against the valve seat, fluid flow is prevented from passing through the fluid passageway. The hollow cylindrical float assembly is positioned above the valve seat so that the fluid can rise to a higher level within the storage tank before the float assembly rises and closes the poppet against the valve seat.
In another aspect of the invention, a check-ball valve is provided in the fluid flow passageway upstream with respect to the poppet valve. The check-ball valve allows excess fuel above the valve to escape into the storage tank after pumping pressure of the fluid has ceased. When. the poppet valve is closed and fel flow stops, a certain amount of excess fuel is trapped in the valve housing above the poppet valve. When fluid flow is shut off, the pressure is relieved, the check-ball valve unseats from the check-valve seat and fiel is allowed to bleed through the orifice into the storage tank.
The bleed valve may also have other configurations such as a flexible membrane wherein the flexible membrane expands across a pair of annular extensions extending inwardly into the flow path forming a recess therebetween. Another draw assembly may include a poppet valve in a bore providing a recess structure in the fluid flow passageway upstream from the poppet valve. The check-ball and spring are disposed within a counter-bore of the bleed valve.
Other objects, advantages and applications of the present invention will become apparent to those skilled in the art when the following description of the best mode contemplated for practicing the invention is read in conjunction with the accompanying drawings.